Re: Multiple dispatch problem with swap()
On Apr 22, 6:22 pm, Marcel M=FCller wrote:
I have a base class that provides a swap() method.
In a derived class I have some caching. Swapping the Base slice makes
sense, but it invalidates the cache. No problem if *this is the derived
class, I could simply override swap. But what if the derived class is
the argument to swap?
class Base
{
virtual void swap(Base& right);
};
class Derived
{
int SomeCache;
virtual void swap(Base& right);
}
Base b();
Derived d();
b.swap(d);
Then Base::swap is called, which obviously knows nothing about Derived.
Is there a way to come around that?
I think the design is questionable. If you want to protect your
objects from outsiders messing with the subobjects (like the base
class subobject of a Derived object), you generally make this
subobjekt private. Obviously, this rules out public inheritance. Also,
myDerivedObj.swap(myBaseObj); seems very wrong. What are you actually
trying to achieve here?
Cheers!
SG
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